1. Field of the Invention
The present invention relates to the field of communications, and particularly relates to a method and system for adjusting channel power on the basis of the positional information of at least one area restricted self-organizing subnet (or subnetwork).
2. Description of the Related Art
In a case where dense wireless channels are utilized, in the environment of Wi-Fi 802.11b/g or Wi-Fi Direct of 2.4 GHz Wireless Technology, in general, well-used channels, whose frequency bands do not overlap, are the first channel (2412 MHz), the sixth channel (2437 MHz), and the eleventh channel (2462 MHz). However, in 5 GHz Wireless Technology being developed, there are four available channels in a range of 5.725-5.825 GHz. With the increase of the number of self-organizing subnets sharing a same channel, co-channel interference generated on the basis of these self-organizing subnets increases at the same time. As a result, when it is necessary to transmit important data in a self-organizing subnet, the quality of communications of this self-organizing subnet may not be guaranteed.
In U.S. Patent Application Publication No. 2007/0133483 A1, a method of controlling transmission power on a node over a wireless ad-hoc network, which includes a plurality of sender, intermediate, and receiver nodes, is disclosed. Initially, levels of the transmission power of the node are configured. The node then exchanges information with its neighboring nodes by sending out a global signal. After exchanging the information, the node identifies a node coverage for the level of the transmission power. The node then determines an effective transmission power (ETP). Finally, the EPT is used to form a virtual cluster. However, in this method, the positional information of the node and its neighboring nodes is not utilized, and only the power adjustment of a single node is carried out.
In U.S. Patent Application Publication No. 2006/0217062 A1, a wireless channel resource adjustment method is disclosed. A terminal node receives a transmission request together with a related quality-of-service (QoS) requirement sent from another node, and then it decides a transmission power on the basis of the information carried by the transmission request and the related QoS requirement. However, in this method, the positional information and priorities of the terminal node and the other node are not utilized, and only the transmission power of a single terminal device (i.e., the terminal node) is decided on the basis of the transmission request and related QoS requirement sent from the other node.
In International Publication No. WO 02/03567 A2, a power control technique in wireless network for reducing mobile nodes' power consumption and achieving a lower signal-to-interference ratio is disclosed. The proposed power control scheme for distributed networks discloses a method for adapting and storing the power level for transmission between nodes. For each node that communicates with other nodes in the network, the power level is calculated and stored in the nodes' memories (power caches). Each node continuously builds up its power cache. The calculation of the required transmission power level is done either at the receiving node or at the transmitting node. The resulting calculated power level is stored at the transmitting node for reference and for use in future transmissions. However, in this technique, the positional information and priority of each node are not utilized, and only the transmission power having a certain level of QoS, of a single node is determined on the basis of the relationship between the premeasured transmission power and QoS.
Therefore, it is necessary to provide a technique by which it is possible not only to adjust the channel power of each self-organizing subnet but also to guarantee good communications quality.